The subject of the invention is a point rail of the type comprising a head, a web and a base, used in railway switching gears and associated with a running track called the stock rail.
Such a point rail makes it possible to guide a railway vehicle as chosen either along, or branching from a route, by changing its position, either applied against the adjacent stock rail or separated from it, respectively.
Currently known point rails are of several types:
V--of a shape identical to the Vignoles rail R of the running track. PA1 A--of a shape similar to the Vignoles rail with a thick web. PA1 B--of a very squat shape with a very thick web which is asymmetric with respect to the head and includes a thick base which is asymmetric with respect to the head and with respect to the web. PA1 C--of a shape similar to the Vignoles rail but of smaller height.
In order to bring together the bases of the point rail and the stock rail, point types of shapes V and A require removal by machining, both for the point rail and for the adjacent stock rail, of part of the base, which affects the stability and mechanical strength of both of the rails. Furthermore, the adjacent stock rail which, in the case of switching gears incorporated with long welded rails (LWR), is subjected to strong longitudinal stresses, takes on, by this machining, a tendency to buckle. Since the point rail and the stock rail are of the same height, and the base of the point rail is at least partially absent, it is unavoidably necessary to eliminate the inner fastening of the adjacent stock rail to the sleepers in this region. The continuity of transmission of the longitudinal, vertical and transverse forces to the sleepers and the track support is thereby impaired.
The type of profile with the shape B is of a short height, and consequently has weak resistance to the strong vertical forces. In order to be able to make a link with the running track rail, this profile must undergo difficult forging at its end, which requires, between the head and the base, a large surplus of material in order to overcome, during forging, the difference in height. The great asymmetry of the base and the web causes deformations during the cooling after rolling, and during the heat treatment. This requires demanding subsequent finishing operations.
The type of profile with the shape C, although eliminating some drawbacks of shapes V, A and B, proves to have insufficient horizontal and vertical strength and to be too flexible during switching operations. It generally suffers from a lack of material during forging. For this reason, the connection to the running track rail, instead of forging of the point rail, requires a reduction in the height of the running rail, which then localizes the welding for linking the two in a section of smaller height.
In the running track, the rail is positioned conventionally inclined inwards relative to the track in order to promote centering of the axle in conjunction with the conicity of the tire.
In order to avoid any discontinuity in running, especially in tracks for high-speed traffic, it is essential to retain this inclination of the rail in the switching gear. The point rail, for reasons of deformation and forces during operation, must have the base positioned horizontally, which has the result, in the case of point rails of types V, A, B and C with their running surface horizontal, of providing the tire with a running surface which generates a discontinuity when crossing the point rail.